.

node_modules/mem/readme.md

@@ -0,0 +1,167 @@
+# mem [![Build Status](https://travis-ci.org/sindresorhus/mem.svg?branch=master)](https://travis-ci.org/sindresorhus/mem)
+
+> [Memoize](https://en.wikipedia.org/wiki/Memoization) functions - An optimization used to speed up consecutive function calls by caching the result of calls with identical input
+
+Memory is automatically released when an item expires.
+
+
+## Install
+
+```
+$ npm install mem
+```
+
+
+## Usage
+
+```js
+const mem = require('mem');
+
+let i = 0;
+const counter = () => ++i;
+const memoized = mem(counter);
+
+memoized('foo');
+//=> 1
+
+// Cached as it's the same arguments
+memoized('foo');
+//=> 1
+
+// Not cached anymore as the arguments changed
+memoized('bar');
+//=> 2
+
+memoized('bar');
+//=> 2
+```
+
+##### Works fine with promise returning functions
+
+```js
+const mem = require('mem');
+
+let i = 0;
+const counter = async () => ++i;
+const memoized = mem(counter);
+
+(async () => {
+	console.log(await memoized());
+	//=> 1
+
+	// The return value didn't increase as it's cached
+	console.log(await memoized());
+	//=> 1
+})();
+```
+
+```js
+const mem = require('mem');
+const got = require('got');
+const delay = require('delay');
+
+const memGot = mem(got, {maxAge: 1000});
+
+(async () => {
+	await memGot('sindresorhus.com');
+
+	// This call is cached
+	await memGot('sindresorhus.com');
+
+	await delay(2000);
+
+	// This call is not cached as the cache has expired
+	await memGot('sindresorhus.com');
+})();
+```
+
+
+## API
+
+### mem(fn, [options])
+
+#### fn
+
+Type: `Function`
+
+Function to be memoized.
+
+#### options
+
+Type: `Object`
+
+##### maxAge
+
+Type: `number`<br>
+Default: `Infinity`
+
+Milliseconds until the cache expires.
+
+##### cacheKey
+
+Type: `Function`
+
+Determines the cache key for storing the result based on the function arguments. By default, if there's only one argument and it's a [primitive](https://developer.mozilla.org/en-US/docs/Glossary/Primitive), it's used directly as a key, otherwise it's all the function arguments JSON stringified as an array.
+
+You could for example change it to only cache on the first argument `x => JSON.stringify(x)`.
+
+##### cache
+
+Type: `Object`<br>
+Default: `new Map()`
+
+Use a different cache storage. Must implement the following methods: `.has(key)`, `.get(key)`, `.set(key, value)`, `.delete(key)`, and optionally `.clear()`. You could for example use a `WeakMap` instead or [`quick-lru`](https://github.com/sindresorhus/quick-lru) for a LRU cache.
+
+##### cachePromiseRejection
+
+Type: `boolean`<br>
+Default: `false`
+
+Cache rejected promises.
+
+### mem.clear(fn)
+
+Clear all cached data of a memoized function.
+
+#### fn
+
+Type: `Function`
+
+Memoized function.
+
+
+## Tips
+
+### Cache statistics
+
+If you want to know how many times your cache had a hit or a miss, you can make use of [stats-map](https://github.com/SamVerschueren/stats-map) as a replacement for the default cache.
+
+#### Example
+
+```js
+const mem = require('mem');
+const StatsMap = require('stats-map');
+const got = require('got');
+
+const cache = new StatsMap();
+const memGot = mem(got, {cache});
+
+(async () => {
+	await memGot('sindresorhus.com');
+	await memGot('sindresorhus.com');
+	await memGot('sindresorhus.com');
+
+	console.log(cache.stats);
+	//=> {hits: 2, misses: 1}
+})();
+```
+
+
+## Related
+
+- [p-memoize](https://github.com/sindresorhus/p-memoize) - Memoize promise-returning & async functions
+
+
+## License
+
+MIT © [Sindre Sorhus](https://sindresorhus.com)